Drill bit



Jan. 29, 1963 R. H. HoLslNG 3,075,593

DRILL BIT Filed Nov. 18, 1959 22 3 Sheets-Sheet l 23 myn/raz.'

22 F|G| ROBERT H. flo/.snm

' BY @rada/MUM f7 Tra k/yfrs Jan. 29, 1963 RIH. HoLslNG 3,075,593

y DRILL BIT Filed Nov. 18, 1959 3 Sheets-Sheet 2 l/ T fa, W-

RoERr H Hol-SING uw@ Wfq FIG. 5 vn-ofwfm.

Jan. 29, 1963 R. H. HoLslNG 3,075,593

DRILL BIT Filed Nov. 18, 1959 5 Sheets-Sheet 3 WYE/V702: Ro/:WT H. HoLs/NG 37 fam/dy "im Firmas/f7.5,

United States Patent O 3,675,593 DRILL lil'l Robert H. Helsing, Canton, (rhin, assigner to The 'limiten Relier Bearing Company, Canton, hio, a corporation of @hin Filed Nov. ld, 1959, Ser. No. 853,934 3 Claims. (Cl. iS--Sn The present invention relates to drill bits of the type in which a plurality of cutting bits are removably retained on the face of a bit holder.

It is an object of the present invention to provide a drill bit comprising a bit holder and a plurality of cutting bits.

Another object of the present invention is to provide a drill bit wherein the cutting bits are retained in the bit holder by a tapered friction lock. Still another object is to provide a cluster bit wherein the cutting bits have engaged portions which prevent relative movement therebetween.

Another object of the present invention is to provide a cluster bit in which the cutting bits can be removed from the bit holder by forcing a tapered wedge under the heel of the shank portion of the cutting bit.

A further object is to provide a cluster bit wherein the cutting bits are grouped radially. Another object is to provide a cluster bit arrangement having a pilot nit mounted forward of the other cutting bits.

The cluster bit of the present invention has the out standing advantage over present bits that each individual cutting bit can be rotated on its own axis to obtain a new gauge cutting edge without aecting any other bit in the group.

Another advantage of the present invention is that the individual cutting bits are provided with abutting shoulders which keep them from turning when the drill is used, thus keeping the gauge diameter of the hole more accurate.

Another advantage is the interchangeability of reusing usable parts from a damaged or worn-out bit assembly in another bit assembly for complete use of the parts.

Still another advantage of the present invention is that the tapered friction lock retains the cutting bits in the bit holder without their bottoming on the bit holder, either at the small end of the bit or at the forward face of the bit holder. A tapered friction lock combined with a positive shoulder or bottom -stop becomes loose during the continual hammering to which the bit is subjected in use.

These 'and other objects and advantages will become apparent hereinafter. f

The present invention comprises a cluster bit including a plurality of cutting bits retained in a bit holder and further consists in the parts and combinations and arrangements of parts hereinafter described and claimed.

In the accompanying drawings, which form part of the specification and wherein like symbols refer to like parts wherever they occur,

FlG. l is a partially broken side elevational view of a cluster bit embodying the preferred form of the present invention,

FIG. 2 is an end elevational view of the cluster bit shown in FIG. l,

FIG. 3 is a side elevational view of a modification of the present invention,

FlG. 4 is an end elevational View of the modification shown in FlG. 3,

FIG. 5 is a side elevational view of a modification of the present invention,

FiG. 6 is a side elevational view of another modication of the present invention,

Patented dan. 29, ld@

PEG. 7 is an end elevational view of the modification of the present invention shown in FIG. 6,

FIG. 8 is a side elevational view of another modification of the present invention, and

FIG. 9 is an end elevational view of the modiiication shown in FIG. 8.

FIG. l shows a drill bit 1d including a bit holder ll having a shank l2 adapted to engage a drill rod i3. The bit holder 1l has a front face le which is provided with tapered sockets 15. Each socket l5 tapers inwardly from an open end -at the forward -face i4 of the bit holder ll to a base wall 17 which is smaller' than the open end.

Each of the cutting bits ILS comprises a head portion 19 including a cutting face 2d, hardened cutting inserts 2l, and flattened sides 22 terminating in a shoulder 23 opposed to the cutting face 2b, and a tapered shank portion 24 ending in a small butt end 26. The tapered shank portion 24 forms a friction lock with the correspondingly tapered ysocket 1S in the bit holder 1l.

When the cluster bit 1d is in use, the flattened sides 22 of the cutting bit 18 abut against corresponding sides 22 on other bits i8, thus preventing relative rotation between the bits 18. The shoulder .'43v of the bit head i9 does not touch the front face 14 of the bit holder ll, and the small end 26 of the tapered shank 24 does not engage the base wall 17 of the bit socket l5. The tapered friction lock maintains an engaged relation even during heavy use, whereas bits utilizing a tapered friction lock combined with a positive shoulder or bottom stop become loose in continued use.

The bit holder 1l is provided with openings 30 communicating with the tapered sockets l5. A drift pin 3l having a tapered iiattened shoulder 32 is inserted into the opening 3d to loosen the cutting bits 38. The shoulder 32 of the drift pin 3l engages the small end 26 of the cutting bit shank 24, and as the pin 3l is forced further into the opening 3d, it forces the cutting bit 18 outward, unlocking it from the bit holder l1. In place of the drift pin 3l, the cutting bits 18 can be removed by the application of fluid or air pressure to the small end or bottom area 26 of the bit liti. The bits 18 also can be removed by forcing a tapered wedge between the small bit 'shoulder 23 and the holder face 14.

The bit holder ll is also provided with a passage 36 opening on the face i4 whereby iiuid or air can be forced into the cutting area to carry the rock chips away from the cutting area.

lt is intended that either carbide insert bits or all steel bits can be used in this construction. Either single edge bits commonly known as chisel bits or multiple edge bits are suitable for use in the present invention.

The outer periphery of the cutting face 2li is defined by the outermost edges of the hardened cutting inserts 2l. The diameter of the cutting face Zi) must be greater than the diameter of the bit holder l1 to drill a clear hole which will hold the bit holder ll.

The small cutting bits 18v must be grouped radially in the bit holder 11 rather than in a single or double line. Radially grouped I'bits provide more speed when drilling because of the better coverage, and increase the life of the bit. The large number of cutting edges provided by the cluster bit construction of the present invention also adds to the life of the bit and to the speed of drilling. The present cluster bit provides more uniformly smaller chips when drilling, and these chips are more easily moved from the -hole than large uneven chips. When the portion of a bit insert that defines the gauge diameter of the hole becomes worn, it is not necessary to discard the bit, since it can merely be turned a quarter turn and a new insert is presented to the gauge diameter. This is of considerable importance, since it increases the life of 3 the bit at least lfourfold, besides giving a more constant gauge diameter and a more constant degree of sharpnes to the cutting face.

if desired, the bit holder il can be rnade oi a special material and heat treated to stand excessive hammering blows, while the bits l can be made from material suitable for Grazing or otherwise attaching the cutting inserts 2li.

FIGS. 3 and 4 show a modication of the present invention wherein a pilot or lead bit d@ extends beyond the cutting area deiined by the cutting faces 2d oi the cutting bits "Ehe outer periphery oi the cutting area is determined by the edge of the harder d inserts 2i outermost from the center oi" the bit holder il rthis arrangement of cutting bits has considera' le advantage to certL i: types of soil and rock.

FlG. 5 shows still another niodilication of this invention wherein more than four cutting bits 5.3 are provided. rthis arrangement is adapted to have abutting sli-oui and a pilot bit, if desired. Sno of the advantages of tl construction is that abrasive resistant bits can be used on the outer edges of the bit holder, and shock resistant bits lili; on the inside cluster.

A modication of the present invention shown in FGS. 6 and 7 provides the cutting faces of the insert bits in the same plane, but utilizes chisel its di. The ou er periphery of the cutting area 2d is defined by the edges of the hardened. inserts l2 outermost from the center of the holder ill.

in a further modiiication shown in FiGS. 8 and 9, the insert bits in are set in the bit holder il. at angle. The center bit 33 is a pilot or lead bit sirnilar to the construction shown in FlGS. 3 and 4. This type construetion has certain advantages in sorne drilling situations.

Thus, it is apparent that there has been provided a novel drill bit including a bit holder retaining cutting bits havistU abutting shoulders to restrain rotation between the cutting bits, and a tapered friction lock retaining the cut-4 ting bits in the bit holder, which fulfills all of the objects and advantages sought therefor,

rthis invention is intended to cover all changes and modifications of the examples of the invention herein chosen for purposes of disclosure which do not constitute departures from the spirit and scope of the invention.

Twhat is claimed is:

i. A drill bit comprising a drill bit holder provided with a plurality of open ended taoered s chets, a plurality of cutting bits comp sing head portions having a plurality of equally spaced slots therein, and tapered shank portions terminating in butt ends constructed and arranged to engage the tapered sockets in the bit holder thereby forming the only contact between said bits and said holder, and cutter inserts retained in the slots of the bits, he outer peripheral edges of the cutter inserts defining the gauge diarneter of a cutting area, said bits being constructed and arranged to tighten the connection between the Shanks and the sockets during drilling, said bits being rotata le when disengaged from the sockets to present new distinct cutting edges to the gauge diameter of the cutting area before being reground, said number orc new cutting edges corresponding 'to the number of slots and inserts of the cutting bits.

2. A drill bit comprising a drill bit holder provided with four open ended tapered sockets and singularly inclined passageway/s connecting the bases of said soclie with an outer side wan of said holder, the centerline ot said sockets being parallel to the centerline of said bit holder, each oi said passageways being equally anguiarly related to the bases of said sockets, four cutting bits coniprising head portions each provided with four equally spaced slots therein, each of said bits including side walls having substantially equally spaced iiattened areas thereon, and tapered shank portions terminating in butt ends constructed and arranged to engage the taleered sockets in the bit holder thereby forming the only Contact between said bits and said holder, and cutter inserts retained in the slots of the bits defining a cutting area, said bits being constructed and arranged to tighten the conne. ion be tween the Shanks and the sockets during drilling and removable from the sockets by a force applied through the angularly inclined bit holder passageways against substantially the entire butt end of the bits, each of said cutting bits being retained in a predetermined xed positic-n in the bit holder through the engagement a ila*- tened with a flattened side on an adjacent bit, said cutting bits being rotatable when disengaged from the sockets to present four distinct cutting edges to the gauge diameter of the cutting area before being reground.

3. A drill bit comprising a drill bit holder Jrovided with tour open ended tapered sockets, comprising head portions each provided with iour equally spaced slots therein, each of said bits includinT side walls haring substanti^lly equally spaced .flattened areas thereon, and tapered shank portions terminating in butt ends constructed and arranged to engage the tapered sockets in the bit holder 'thereby forming die only contact between said bits and said holder, and cutter inserts retained in the slots 0f the bits, the outer peripheral edges of said cutting inserts defining the gauge diameter of a cutting area, said bits being constructed and arranged to tighten the connection between the shanlrs and the sockets during drilling, each ot said cutting bits being retained in a predetermined xed position in the bit holder through the engagement of a liattened side with a flattened side on an adjacent bit said cutting bits being rotatable when disengaged from the sockets to present four distinct cutting edges to the gauge diameter of the cutting area before being reground.

Reierences @lied in the file of this patent UNETED STATES PATENTS 63,681 White Apr. 9, 1867 884,159 Hardsocg Apr. 7, 1908 967,360 Hoffman Dec. 22, i908 1,589,596 Hokanson lune 22, 1926 1,830,625 Schreck Nov. 3, 1931 2,145,262 Holcanson ian. 31, 1939 2,203,216 Holtanson lune 4, 1960 2,955,810 licWhorten et al Oct. 11, 1950 FOREIGN PATENTS 23,730 Great Britain Oct. 28, 1899 OTHER REFERENCES serial No. 384,737, application of A. Mensch (Arno), published May 25, 1943.

four cutting 

1. A DRILL BIT COMPRISING A DRILL BIT HOLDER PROVIDED WITH A PLURALITY OF OPEN ENDED TAPERED SOCKETS, A PLURALITY OF CUTTING BITS COMPRISING HEAD PORTIONS HAVING A PLURALITY OF EQUALLY SPACED SLOTS THEREIN, AND TAPERED SHANK PORTIONS TERMINATING IN BUTT ENDS CONSTRUCTED AND ARRANGED TO ENGAGE THE TAPERED SOCKETS IN THE BIT HOLDER THEREBY FORMING THE ONLY CONTACT BETWEEN SAID BITS AND SAID HOLDER, AND CUTTER INSERTS RETAINED IN THE SLOTS OF THE BITS, THE OUTER PERIPHERAL EDGES OF THE CUTTER INSERTS DEFINING THE GAUGE DIAMETER OF A CUTTING AREA, SAID BITS BEING CONSTRUCTED AND ARRANGED TO TIGHTEN THE CONNECTION BETWEEN THE SHANKS AND THE SOCKETS DURING DRILLING, SAID BITS BEING ROTATABLE WHEN DISENGAGED FROM THE SOCKETS TO PRESENT NEW DISTINCT CUTTING EDGES TO THE GAUGE DIAMETER OF THE CUTTING AREA BEFORE BEING REGROUND, SAID NUMBER OF NEW CUTTING EDGES CORRESPONDING TO THE NUMBER OF SLOTS AND INSERTS OF THE CUTTING BITS. 